Following the maxims ‘bigger is better’ or ‘be prepared,’ a number of homes are constructed or renovated with furnaces that are too large for the home. Additionally, homeowners trying to economize frequently block, close or shut off the vent covers or air registers to one or more rooms in their home, thereby creating cooler zone(s) in some areas and warmer zone(s) in other areas, thereby changing the time of furnace operation. Similarly, evolving technologies are able to automatically open and close the doors on vent covers in one or more rooms, thereby attempting to put heat where and when it is most needed.
In each of these examples, insufficient air may be moved through heat exchangers within the furnace. This can result in the furnace operating at a higher temperature than is preferred, possibly even causing a thermostatically-controlled safety switch to turn the furnace off until it cools.
Accordingly, the foregoing factors, alone or in combination, can result in inadequate airflow through a furnace and potentially overheating of the furnace.